You definitely do not want 3/8ID 1/2OD unless you are using anti kink coils on the tubing. It has horrible bend radius. Like I said in the PM 3/8ID 5/8OD Primoflex LRT is the way to get IMO. The difference in flow between 3/8ID and 1/2ID is pretty much meaningless. Plus the fact that 3/8ID has improved bend radius.

Hey you guys never give me these info when I first build my WC few month ago! grrrr...I have to agree 1/2 OD is dead hard to bend so you have damn long tube running eevrywhere just because you can't bend them. Look at lowfat workblog, he can alsmo bend histubing 90 degree. Their advice are good;)

heh, yeah, thats where my questions originally came from, was looking through some worklogs, saw lowfats, sent him a pm, then decided to stop bugging him and ask everyone im glad i got this info before picking out components. Everyone is so helpful

I've used 7/16 ID and 5/8" OD, it was pretty good, but I can't comment on the sharp turns because I used anti kink coils. I am currently using 1/2ID and 3/4OD and really like the look, can do some pretty sharp turns too. I believe the above posters have had the chance to try all sizes. A thick wall is definitely best for turn radius.